The known contact photolithographic techniques allow the achievement of metal lines less than 1 .mu.m width on a substrate, with very good yields. However, when lines less 0.5 .mu.m width are desired, these techniques are unsuitable because of intrinsic limitations of the technique itself. In order to overcome this limitation, various methods and technologies based upon, e.g., the use of electronic beams or X-rays are used, which require very expensive and complex equipment as well as complex and expensive facilities for the realization and control of the process.